Any Art History Majors in here?

Who is he lecturing to? Art lovers on a cruise or a tour of university arts societies?

If it is to art lovers then he might focus on one artist or school eg. Caravaggio; mad genius or charlatan?

Lectures on local subjects are often popular, so maybe famous and semi-famous local artists of the past.

How much is he/she getting paid?

I had an art history prof who published a book on Princess Diana. I'm guessing, as part of any prof's research and publication requirement, she gave speeches to support her theories/claims.

Another art history prof was an expert in fabrics (I guess the decor??). I think they can give speeches on anything that's even closely related to art/history as long as that is their focus.

Figure out who your audience is first. Then consider that the Professor would be prepared to lecture on what they are interested in.

Mystery buffs might be entertained with a speech about famous art heists and forgeries, for instance.

My college in Philadelphia held a regional alumni event here in Atlanta. The High Museum was doing a big exhibit on Andrew Wyeth, so they had someone come down and do a lecture about the three generations of artists in the Wyeth family and some of the backstory on the paintings that we might not get from doing the tour.

It depends what the professor did his or her PhD in. Someone who's intimately familiar with baroque architectural detail isn't going to lecture on art deco prints, no matter who the audience is.

When we've had guests they have been invited by the univeristy to speak, they generally haven't contacted the university themselves. Usually they are contacted with a brief in mind, such as 'we're doing a series on french cinema, would you like to talk about xxxxxx' and beyond that the lecture is usually up to the guest.

Or sometimes someone who is having sucess at that time, or a new book out, or media interest etc will be asked to speak on thier own topic of choice, but that's often more a PR thing than an academic one, and those lectures are generally on at night.